A transaction advisor is a practitioner in a firm's Transaction Advisory Services (TAS) practice — most associated with the Big Four (Deloitte, EY, KPMG, PwC) and large independent advisory firms — who provides the financial, tax and operational diligence and structuring support around an M&A deal. TAS is the institutional, scaled form of the M&A accountant role, deployed on mid-market and large transactions.
What TAS provides
Transaction advisors offer an integrated suite of deal services, on either side of a transaction:
- Financial due diligence / quality of earnings — the QoE report testing Adjusted EBITDA, add-backs, revenue quality, net working capital and net debt. The flagship product.
- Tax diligence and structuring — tax exposures, deal structure, elections and reorganizations.
- Operational and commercial diligence — synergy assessment, IT, carve-out and supply-chain review.
- Integration and separation support — 100-day planning, synergy realization and carve-out execution.
- Valuation and post-close accounting — purchase price allocation under asc-805/ifrs-3 and opening balance sheets.
Buy-side and sell-side
TAS works for both sides of a deal:
- Buy-side — diligence to protect the buyer: confirming earnings, surfacing risks, informing the price and the agreement (re-trades, escrow, indemnities).
- Sell-side — a vendor due diligence (VDD) report or sell-side QoE prepared before launch to validate the numbers, pre-empt buyer challenges and smooth the process (one of the highest-ROI items in deal prep).
Why it is separate from audit
A defining feature of TAS is that it is organizationally and ethically distinct from the firm's audit practice. Independence rules generally bar a firm from providing deal-advisory work to its own audit clients in ways that would impair auditor independence, so TAS engagements are structured to respect those boundaries. TAS is advisory — investigative, deal-focused, and not a statutory audit (it issues no audit opinion).
How it relates to bankers and lawyers
The transaction advisor sits alongside, not in place of, the other advisers: the investment banker or M&A advisor runs the process and valuation/negotiation; the M&A lawyer owns the documents; the transaction advisor owns the numbers and diligence. On a typical mid-market or large deal, all three work in parallel for the buyer (or the seller), each feeding the definitive agreement from their domain.
See also
- M&A accountant — CPA or transaction-services accountant who runs quality-of-earnings analysis, working-capital benchmarking, tax structuring and post-close purchase-price allocation work.
- Quality of earnings — An independent accounting analysis that tests how sustainable, predictable and accurately measured a target's reported earnings are. The QofE is a near-universal pre-LOI deliverable in serious deals.
- Quality of earnings report — The formal deliverable from a quality-of-earnings engagement — a third-party accountant's analysis of a target's reported earnings, normalisation adjustments and revenue and cost trends.
- Due diligence — The structured investigation a buyer conducts on a target between LOI and closing — covering financial, legal, tax, commercial, operational, IT, HR and environmental workstreams — to verify the seller’s claims, find risks and shape final price and deal terms.
- Post-merger integration — The combination of the two organisations' operations, systems, people and culture after closing. Most acquisitions that destroy value do so in PMI, not at the deal-pricing stage.
- Tax due diligence — The tax-focused workstream of buy-side diligence: federal/state/local income tax exposure, sales-and-use tax, payroll tax, transfer pricing, R&D credits, and the tax history of the target entity.